Applied Mechanics and Materials Vols. 444-445

Abstract: CFD simulation study on the fire-extinguishing performance of ultra-fine water mist (UFM) and its flow behavior in a small scale tunnel. Numerical simulation using dense gas model were carried outIt is discorvered that simulation shows that the larger size of fire is more difficult to extinguish in tunhenel space; and that the effect of obstruction in extinguishing efficiency depends on the location of obstruction.

Abstract: The computer simulation has become an important means to study fire broke out and its law of development today. Fire Dynamics Simulator is three-dimensional computational fluid dynamics software based on LES. And it is widely used in the field of fire science. However, it is rarely used in the study of forest fires. Through the study of tree morphological parameters,combined with the modeling features of the pre and post-processing graphical software PyroSIM, this article explored a tree modeling method for FDS.

Abstract: The field investigation of the human evacuation behavior of young people under time pressure in campus is conducted in Northeastern University of Shenyang. Based on the analysis of the observation of human evacuation behavior characteristics, scenarios of human evacuation in academic building under different evacuation management strategy are simulated and compared by FDS+Evac. The analysis results show that the crowd flow coefficient will be increasing under time pressure. The congestion of the crowd in academic building can be alleviated effectively on the base of batches evacuation management. The Real Safety Evacuation Time (RSET) can be reduced if the layout of exits is designed felicitously. Therefore, emergency drill such as fire drill is suggested to proceed periodically and regularly so that human can have opportunity to experience emergent and hazard surroundings to improve their ability of evacuation in emergency.

Abstract: Safety evacuation design is a key content for building fire safety design. In this paper, we apply the CAFE model to conduct an one-exit room simulation. And then we establish the regression equation of exit flow rate considering the factors of the exit width, the size of the room, the location of the exit and the pedestrian density. So as to find the effect of the exit location on the exit flow rate, we analyze the correlation of the two variables. It is found that the exit flow rate of large room is easily affected by the exit location. And it proves that the exit flow rate decreases with the increase of the exit location. At last we study the probability distribution of the number of pedestrians evacuating through the exit and list some reasons why the exit flow rate decreases with the increasing exit width.

Abstract: A numerical study of premixed propane/air flame propagation in a closed duct is presented. A dynamically thickened flame (TF) method is applied to model the premixed combustion. The reaction of propane in air is taken into account using a single-step global Arrhenius kinetics. It is shown that the premixed flame undergoes four stages of dynamics in the propagation. The formation of tulip flame phenomenon is observed. The pressure during the combustion process grows exponentially at the finger-shape flame stage and then slows down until the formation of tulip shape. After tulip formation the pressure increases quickly again with the increase of the flame surface area. The vortex motion behind the flame front advects the flame into tulip shape. The study indicates that the TF model is quite reliable for the investigation of premixed propane/air flame propagation.

Abstract: The Wall Adpating Local Eddy Viscosity (WALE) subgrid-scale turbulence model was adopted for an in-house large eddy simulation (LES) fire code in which the turbulence is fully coupled combustion and radiation models. The traditional Smagorinsky subgrid-scale model accounts only strain rate of the turbulent structure while the WALE model considers both the strain and the rotation rates. Furthermore, the WALE model automatically recovers the near wall-scaling for the eddy viscosity hence more adaptive for wall bounded flows.A 15 m long test hall fire was reconstructed by the in-house fire code with 1.5 MW fire source. The performance of the WALE model was assessed by comparingpredicted transient gas temperatures and velocities at various spatial locations.

Abstract: This paper simulates the fire prevention performance of external insulation system with curtain wall based on FDS method. The effect to control flame spread of fire-barrier belt and fire separating element with different width is discussed. The characteristics of temperature distribution on the interior, exterior and intermediate cavity of external insulation system are analyzed and the variability of heat release rate is found. The results prove that fire-barrier belt and fire separating element could effectively inhibit flame spread and growth. The fire prevention performance of external insulation system is strengthened with increasing of setting the width. When the width of fire separating element is 100 mm and fire-barrier belt width is 300 mm, the whole external insulation system has good fire prevention performance, which can be set as basic parameters for the design of fire protection construction with consider the applicability and economical efficiency of actual engineering.

Abstract: As the increasing requirement on the scientific nature of fire investigation conclusion, fire numerical reconstruction technology is gradually used in fire investigation work, and it becomes one of the important auxiliary tools. In this paper combustible of the burning coach was analyzed, and two different conditions were set, the development process of heat and smoke, poison and other related information is shown. This indicates that the FDS-method can be combined with other fire investigation ways to support the investigation results.

Abstract: In order to explore the relationship between China's scientific and technological progress and economic growth, granger test is been used on investment in science and technology and economic growth based on the sample period (1995-2010) of economic data.The experimental results show that : the scientific and technological progress and economic growth are each other's Granger causes. The paper divide the investment of science and technology into the manpower investment and financial investment in the analysis of economic growth and investment of science and technology the causality, then do Granger causality test on economic growth index GDP.

Abstract: The development of medical E-commerce is facing many challenges and constraints from government, businesses, individuals and other aspects. This paper, on the basis of the full investigation, elaborates Interpretative Structural Modeling (ISM) to make qualitative analysis. The modeling shows a clear hierarchical relationship between the various influencing factors and differentiates the surface factors, shallow factors, middle factors and underlying factors to expect to provide some suggestions for the development of medical E-commerce, and also lay the theoretical foundation for the quantitative analysis.